In past studies with rodent tumors (1-3), the present inventor found that it was necessary to coadminister N-(phosphonoacetyl)-L-aspartate (PALA) and 5-fluoro-2′-deoxycytidine (FdC) plus tetrahydrouridine (H4U) or 5-fluoro-2′-deoxyuridine (FdU) with 5-chloro-2′-deoxycytidine (Cytochlor, CldC) to achieve clinically relevant radiosensitization. The inventor stated and published (1-3) that the protocol was unamenable to modifications, i.e. it was necessary to coadminister three drugs with Cytochlor for biologically significant radiosensitization to occur. The inventor previously followed this protocol utilizing PALA, FdC, H4U and CldC in his studies with human tumors in nude mice.